Autism: When it's more than hearing loss

While the origins of autism remain a mystery, a new study has pointed to the infant hearing loss as a potential predictor.

The University of Rochester researchers identified an inner ear deficiency in children with Autism that may impact their ability to recognize speech. The findings could ultimately be used as a way to identify kids at risk for the disorder at an early age.

"This study identifies a simple, safe, and non-invasive method to screen young children for hearing deficits that are associated with Autism," said co-author Anne Luebke, adding: "This technique may provide clinicians a new window into the disorder and enable us to intervene earlier and help achieve optimal outcomes."

In the study, researchers used a technique that measures what are called otoacoustic emissions. The test is akin to the screening that many newborns must undergo before leaving the hospital to check for hearing problems. Using miniature speaker/microphone earplugs, the researchers were able to measure hearing deficiencies by listening for signs that the ear is having difficulty processing sounds.

They tested the hearing of children between the ages of 6 and 17, roughly half of whom have been diagnosed with ASD. They found that the children with ASD had hearing difficultly in a specific frequency (1-2 kHz) that is important for processing speech. They also found a correlation between the degree of cochlear impairment and the severity of ASD symptoms.

"Auditory impairment has long been associated with developmental delay and other problems, such as language deficits," said co-author Loisa Bennetto. "While there is no association between hearing problems and autism, difficulty in processing speech may contribute to some of the core symptoms of the disease. Early detection could help identify risk for ASD and enable clinicians to intervene earlier. Additionally, these findings can inform the development of approaches to correct auditory impairment with hearing aids or other devices that can improve the range of sounds the ear can process."

Because the test is non-invasive, inexpensive, and does not require the subject to respond verbally, this technique could be adapted to screen infants, an approach that the team is currently exploring.

The study appears in Autism Research.